Background: Biocatalysis is currently progressing from utilising natural enzymes to the development of artificial enzymes with new reactivities. Since the range of metal cofactors in natural enzymes is limited, it is of great interest to incorporate complementary organometallic catalysts within protein scaffolds to create artificial metalloenzymes (ArMs), such as our previously-developed artificial imine reductase (1). The protein scaffold provides a chiral environment that increases the (stereo)selectivity of the catalyst and enables catalytic reactions to be performed in aqueous solution, under biocompatible conditions and as part of biochemical reaction cascades.
Objectives: The aim of this project is to assemble and trap ArMs in E. coli cells by taking advantage of active bacterial iron-uptake, which is mediated by siderophores, molecules that are naturally produced by bacteria. In this way, the bacterial cell may be exploited to support abiotic reactions, for example the production of valuable enantiopure amines or alcohols.
Experimental Approach: Chemical conjugation techniques, such as amide coupling, will be used to attach kinetically inert complexes of mainly d6 low-spin metal ions to the backbone of the siderophore L-azotochelin and its enantiomer D-azotochelin, building upon our previous work. Once purified and characterised, the affinity of the conjugates for selected protein scaffolds, such as the siderophore-binding protein CeuE, will be determined. To guide structural modifications, we will carry out co-crystallisation screens with promising siderophore-anchored catalysts and protein scaffolds. The co-crystal structures obtained will indicate how the environment provided by the protein could be modified by mutagenesis to increase the enantioselectivity of the catalysts.
The catalytic activity tests with the artificial metalloenzymes will be carried out according to procedures already established in our labs. Product formation will be monitored by chiral HPLC analysis and by use of fluorogenic substrates. Periplasmic catalyst concentrations will be determined through metal analysis of osmotic shock extracts by ICP-MS. Parameters that can be varied to optimise catalytic performance include protein expression levels, component structures and concentrations, incubation times and pH.
Training: All Chemistry research students have access to our innovative Doctoral Training in Chemistry (iDTC): cohort-based training to support the development of scientific, transferable and employability skills: https://www.york.ac.uk/chemistry/postgraduate/cdts/
The Department of Chemistry holds an Athena SWAN Gold Award and is committed to supporting equality and diversity for all staff and students. The Department strives to provide a working environment which allows all staff and students to contribute fully, to flourish, and to excel: https://www.york.ac.uk/chemistry/ed/.
For more information about the project, click on the supervisor's name above to email the supervisor. For more information about the application process or funding, please click on email institution
This PhD will formally start on 1 October 2022. Induction activities may start a few days earlier.
To apply for this project, submit an online PhD in Chemistry application: https://www.york.ac.uk/study/postgraduate/courses/apply?course=DRPCHESCHE3
You should hold or expect to achieve the equivalent of at least a UK upper second class degree in Chemistry or a related subject. Please check the entry requirements for your country: https://www.york.ac.uk/study/international/your-country/